1. FIELD OF THE INVENTION
The invention concerns a control device for washing machines, laundry-washing machines in particular, combined with a detergent distributor for the machines, which is capable of selectively regulating the introduction of several detergents into the machines tub for the prewash and washing of laundry contained therein.
2. DESCRIPTION OF RELATED ART
Detergent distributors are known for washing machines such as laundry-washing machines or combined machines for the washing and drying of laundry. They are divided into several separate compartments containing the detergent the prewash, washing and bleaching and/or softening of the wash. In detergent distributors of this type, every compartment may be fed water from the main water supply through a suitable rotating selector that may be set by means of appropriate levers actuated by the machines programmed timer to several positions of operation. In this way, they determine the introduction into the tub of water and detergent or additive respectively contained in such compartment.
Also known are detergent distributors for electronic washing machines equipped with a microprocessor to control the action of the various washing cycles. Detergent distributors of this type are also normally equipped with a rotating selector of the kind mentioned above, which is set to each of its several regulating positions by two small pistons connected to the rotating selector. Each such piston contains wax that can be heated by a PTC element powered electrically through a semiconductor switch suitable for that purpose, such as a triac or similar device connected to the electric circuit of such a machine and to said microprocessor. In this way, the rotating selector of such detergent distributors is set to its various regulation positions by means of the microprocessor. This determines the introduction into the tub of the detergent or additive contained in the specific compartment. The PTC elements are kept ON or OFF or selectively ON by means of the triac by reason of the different heat expansion of the wax of the two small pistons brought about by these ON and OFF switchings of the PTC elements.